FILE - In this Aug. 27, 2008, file photo, former President Bill Clinton speaks at the Democratic National Convention in Denver. The way Democrats and Republicans treat their ex-presidents at convention time reflects each man's personal popularity and also how well he's weathered changes in party politics. It helps to be a dynamite speaker, too. Clinton scores on all three: his speeches are rousing, if long; his popularity extends to coveted independent voters; and his centrist appeal plays well across today's Democratic Party. It's no wonder that Democrats are have forgiven, if not forgotten, that business about Monica Lewinsky and impeachment that seemed to have permanently marred his presidency as it ended a dozen years ago. (AP Photo/Charlie Neibergall, File)

President Barack Obama's one-word campaign slogan is "Forward." But as he prepares to accept his party's nomination for a second term, he's casting backward for help in moving ahead.

Speaking in a time spot usually reserved for the running mate, former President Bill Clinton was addressing the National Convention in Charlotte, N.C. Wednesday to put the president's name in nomination.

Democrats hoped his appearance would remind voters of Clinton's stewardship of a late-1990s economy that was growing and federal annual budgets briefly posted surpluses. It's intended as a contrast with last week's Republican convention in Tampa, Fla., where former GOP President George W. Bush, was barely mentioned.

After watching wife Michelle Obama's opening night speech from the White House with their two daughters on Tuesday, Obama was arriving in Charlotte Wednesday for the festivities.

Obama and Clinton have had a rocky past but are teaming up to present a unified message. Beyond helping Obama sell his economic proposals, Clinton can connect with independents and many working-class voters who haven't warmed to Obama.

Obama and Vice President Joe Biden speak Thursday night. Convention planners say a rain threat is forcing the speeches indoors from a large open-roof stadium.

Mitt Romney remained in Vermont practicing for the upcoming fall presidential debates with sparring partner Sen. Rob Portman, R-Ohio, playing the role of Obama. He left daily campaigning duties to running mate Rep. Paul Ryan, R-Wis., and a Republican "truth squad" encamped in Charlotte to issue GOP counterpoint.

Ryan, stumping Wednesday in Adel, Iowa, called the U.S. "a country in decline," citing a national debt that this week topped $16 trillion.

Which brings us back to Clinton. The debt was $5.7 trillion when he left office in January 2001, increasing to $10.6 trillion under Bush and now hitting $16 trillion under Obama.